The intelligibility of simulated underwater voice communication as measured by the NSMRL Tri‐Word Test of Intelligibility (TTI)

Abstract

Our previous paper suggested the TTI for use in assessing the effect of temporal distortions on speech intelligibility. Here, the TTI is applied in an investigation of the phenomenon of multipath, a temporal distortion which can severely limit the intelligibility of underwater voice communication. Evidence suggests that intelligibility may be improved if speech is time‐reversed prior to underwater transmission. Results are presented for simulated forward and time‐reversed speech conditions across an echo delay range of 50–500 ms as a function of the amplitude of an echo relative to that of the original signal. Asymmetric intelligibility functions are demonstrated which are dependent on the length of echo delay interval. These results are discussed in terms of temporal masking and perceptual fusion effects.